The present disclosure relates to sterile medical fluid delivering and in particular to the delivering of a dialysis solution.
Due to disease or other causes, a person's renal system can fail. In renal failure of any cause, there are several physiological derangements. The balance of water, minerals and the excretion of daily metabolic load is no longer possible in renal failure. During renal failure, toxic end products of nitrogen metabolism (urea, creatinine, uric acid, and others) can accumulate in blood and tissues.
Kidney failure and reduced kidney function have been treated with dialysis. Dialysis removes waste, toxins and excess water from the body that would otherwise have been removed by normal functioning kidneys. Dialysis treatment for replacement of kidney functions is critical to many people because the treatment is life saving. One who has failed kidneys could not continue to live without replacing at least the filtration functions of the kidneys.
One type of dialysis is peritoneal dialysis. Peritoneal dialysis uses a dialysis solution or “dialysate”, which is infused into a patient's peritoneal cavity through a catheter implanted in the cavity. The dialysate contacts the patient's peritoneal membrane in the peritoneal cavity. Waste, toxins and excess water pass from the patient's bloodstream through the peritoneal membrane and into the dialysate. The transfer of waste, toxins, and water from the bloodstream into the dialysate occurs due to diffusion and osmosis, i.e., an osmotic gradient occurs across the membrane. The spent dialysate drains from the patient's peritoneal cavity and removes the waste, toxins and excess water from the patient. This cycle is repeated.
There are various types of peritoneal dialysis therapies, including continuous ambulatory peritoneal dialysis (“CAPD”) and automated peritoneal dialysis (“APD”). CAPD is a manual dialysis treatment, in which the patient connects an implanted catheter to a drain and allows a spent dialysate fluid to drain from the patient's peritoneal cavity. The patient then connects the catheter to a bag of fresh dialysate and manually infuses fresh dialysate through the catheter and into the patient's peritoneal cavity. The patient disconnects the catheter from the fresh dialysate bag and allows the dialysate to dwell within the cavity to transfer waste, toxins and excess water from the patient's bloodstream to the dialysate solution. After a dwell period, the patient repeats the manual dialysis procedure.
In CAPD the patient performs several drain, fill, and dwell cycles during the day, for example, about four times per day. Each treatment cycle typically takes about four hours. APD is similar to CAPD in that the dialysis treatment includes a drain, fill, and dwell cycle. APD machines, however, perform three to four cycles of peritoneal dialysis treatment automatically, typically overnight while the patient sleeps. Like CAPD, APD machines connect fluidly to an implanted catheter, to one or more sources or bags of fresh dialysate and to a fluid drain.
The APD machines pump fresh dialysate from the dialysate source, through the catheter, into the patient's peritoneal cavity and allow the dialysate to dwell within the cavity so that the transfer of waste, toxins and excess water from the patient's bloodstream to the dialysate solution can take place. The APD machines then pump spent dialysate from the peritoneal cavity, though the catheter, to the drain. APD machines are typically computer controlled so that the dialysis treatment occurs automatically when the patient is connected to the dialysis machine, for example, when the patient sleeps. That is, the APD systems automatically and sequentially pump fluid into the peritoneal cavity, allow for a dwell, pump fluid out of the peritoneal cavity and repeat the procedure. As with the manual process, several drain, fill, and dwell cycles will occur during APD. A “last fill” is typically used at the end of APD, which remains in the peritoneal cavity of the patient when the patient disconnects from the dialysis machine for the day.
Delivery of dialysis fluid to the patient needs to be as germ free as possible. Germs or pathogens reaching the patient's peritoneum can cause peritonitis. Peritonitis can cause the patient to feel extreme pain and if not treated properly can result in death. Different methods of sterilization are available, such as gamma radiation and ethylene oxide (“EtO”) gas. Gamma radiation is advantageous because it works from the outside-in, such that the radiation can sterilize the interior surfaces of a structure that trap a volume of gas within the sterilized part, such as a cap.
Gamma radiation does however have some negative side effects. One side effect is that the sterilized part, e.g., clean medical grade plastic, tends to yellow. While such yellowing is not harmful to the patient, some patients may find the yellowed disposable part less aesthetically pleasing than a pristine looking clear plastic disposable. Second, gamma radiation can cause the sterilized part to have an odor, especially when the disposable has larger plastic surfaces, which can also be displeasureable to the patient.
A need therefore exists for an apparatus and method for sterilizing a sealed part, such as a cap, using a sterilizing gas, such as EtO.